6.1 The Cell Cycle Flashcards
What are the 3 stages of mitosis?
Interphase
Nuclear division (mitosis)
Cell division (cytokinesis)
What does the length of the cell cycle depend on?
Environmental conditions, the cell type and the organism.
What is the movement from one phase to another controlled by?
Chemical signals called cyclins.
What happens during interphase?
During Interphase the cell increases in mass and size and carries out its normal cellular functions (eg. synthesising proteins and replicating its DNA ready for mitosis)
What are the three stages of interphase?
G1 phase
S phase
G2 phase
What happens during the G1 phase?
Cells make the RNA, enzymes and other proteins required for growth during the G1 phase
What happens in the S phase?
The DNA in the nucleus replicates (resulting in each chromosome consisting of two identical sister chromatids)
What happens in the G2 phase?
During the G2 phase, the cell continues to grow and the new DNA that has been synthesised is checked and any errors are usually repaired
Other preparations for cell division are made (eg. production of tubulin protein, which is used to make microtubules for the mitotic spindle)
When does mitosis occur and what happens during it?
Follows interphase
Referred to as the M phase – M stands for mitosis
Cell growth stops during the M phase
When does cytokinesis occur and what happens during it?
Follows M phase
Once the nucleus has divided into two genetically identical nuclei, the whole cell divides and one nucleus moves into each cell to create two genetically identical daughter cells
How does cytokinesis happen differently in animal and plant cells?
In animal cells, cytokinesis involves constriction of the cytoplasm between the two nuclei and in plant cells, a new cell wall is formed
How is the cell cycle regulated during the G1 phase?
During G1 phase - chromosomes are checked for damage. If damage is detected then the cell does not advance into the S phase until repairs have been made
How is the cell cycle regulated during the S phase?
chromosomes are checked to ensure they have been replicated. If all the chromosomes haven’t been successfully replicated then the cell cycle stops
How is the cell cycle regulated during the G2 phase?
an additional check for DNA damage occurs after the DNA has been replicated. The cell cycle will be delayed until any necessary repairs are made
How is the cell cycle regulated during metaphase?
the final check determines whether the chromosomes are correctly attached to the spindle fibres prior to anaphase
